Solar cell and method for producing solar cell

Abstract

A solar cell according to one embodiment of the present invention is provided with: an n-type crystalline silicon wafer having an n + layer in the entire wafer surface and in the vicinity thereof, said n + layer having a higher n-type dopant concentration than the other regions; a low concentration P-containing silicon oxide layer which is formed on a light receiving surface of the n-type crystalline silicon wafer; an n-type crystalline silicon layer which is formed on the low concentration P-containing silicon oxide layer; and a p-type amorphous silicon layer which is formed on the back surface side of the n-type crystalline silicon wafer.

1 . A solar cell comprising:
 in an entire wafer surface and a vicinity of the entire wafer surface, an n-type crystalline silicon wafer having an n +  layer having a higher concentration of an n-type dopant than other regions;   a silicon oxide layer formed on a light receiving surface of the n-type crystalline silicon wafer;   an n-type crystalline silicon layer formed on the silicon oxide layer; and   a p-type amorphous silicon layer formed on a rear surface side of the n-type crystalline silicon wafer,   wherein the silicon oxide layer contains an n-type dopant, and   a concentration of the n-type dopant in the silicon oxide layer is lower than a concentration of n-type dopants in the n +  layer and the n-type crystalline silicon layer.   
     
     
         2 . The solar cell according to  claim 1  further comprising a passivation layer formed between the n-type crystalline silicon wafer and the p-type amorphous silicon layer,
 wherein the passivation layer is made with substantially intrinsic amorphous silicon, or an amorphous silicon having a lower concentration of a p-type dopant than the p-type amorphous silicon layer, as a main component. 
 
     
     
         3 . The solar cell according to  claim 1 ,
 wherein a concentration of the n-type dopant in the n-type crystalline silicon layer is 1×10 21  atoms/cm 3  or less.   
     
     
         4 . The solar cell according to  claim 1 ,
 wherein a concentration of the n-type dopant in the n +  layer is 1×10 20  atoms/cm 3  or less.   
     
     
         5 . The solar cell according to  claim 1  comprising:
 a first transparent conductive layer formed on the n-type crystalline silicon layer; 
 a first collector electrode formed on the first transparent conductive layer; 
 a second transparent conductive layer formed on the p-type amorphous silicon layer; and 
 a second collector electrode formed on the second transparent conductive layer. 
 
     
     
         6 . The solar cell according to  claim 1  comprising:
 an n-type amorphous silicon layer formed on a first region on a rear surface of the n-type crystalline silicon wafer; 
 an insulation layer formed in a part on the n-type amorphous silicon layer; 
 the p-type amorphous silicon layer formed on a second region of the rear surface of the n-type crystalline silicon wafer, and on the insulation layer; 
 a first transparent conductive layer formed on the n-type amorphous silicon layer; 
 a first collector electrode formed on the first transparent conductive layer; 
 a second transparent conductive layer formed on the p-type amorphous silicon layer; and 
 a second collector electrode formed on the second transparent conductive layer. 
 
     
     
         7 . A method for producing a solar cell, comprising:
 a first step of submerging an n-type crystalline silicon wafer in an acid aqueous solution containing an n-type dopant, and forming a high concentration n-type dopant-containing silicon oxide layer on an entire surface of the wafer;   a second step of forming an i-type silicon layer with substantially intrinsic amorphous silicon or a substantially intrinsic polycrystalline silicon layer, as a main component, in a region located on one principal surface of the n-type crystalline silicon wafer, of the high concentration n-type dopant-containing silicon oxide layer;   a third step of thermally treating the n-type crystalline silicon wafer, diffusing the n-type dopant to the n-type crystalline silicon wafer and the i-type silicon layer from the high concentration n-type dopant-containing silicon oxide layer, forming, in the entire wafer surface and a vicinity of the entire wafer surface, an n +  layer having a higher concentration of the n-type dopant than other regions, and forming an n-type crystalline silicon layer by crystallizing the i-type silicon layer;   a fourth step of removing a part, of a low concentration n-type dopant-containing silicon oxide layer formed by the n-type dopant being partially removed by the third step, that is exposed without being covered with the n-type crystalline silicon layer; and   a fifth step of forming a p-type amorphous silicon layer on the other principal surface side of the n-type crystalline silicon wafer.   
     
     
         8 . The method for producing a solar cell according to  claim 7  further comprising a step of forming a passivation layer on the other principal surface of the n-type crystalline silicon wafer,
 Wherein the p-type amorphous silicon layer is formed on the passivation layer, and 
 the passivation layer is made with substantially intrinsic amorphous silicon, or amorphous silicon having a lower concentration of p-type dopant than the p-type amorphous silicon layer, as a main component. 
 
     
     
         9 . The method for producing a solar cell according to  claim 7 ,
 wherein in the step of diffusing the n-type dopant, the n-type crystalline silicon wafer is thermally treated at a temperature of 800° C. to 1000° C.   
     
     
         10 . The method for producing a solar cell according to  claim 7 ,
 wherein a treatment temperature in the step of forming the n-type dopant-containing silicon oxide layer is 10° C. to 90° C.